The long-term goal of this research proposal is to validate allosteric inhibition as a general mechanism of regulation in caspases. The specific aims of the proposal are: 1) identify small molecule inhibitors of human caspase-1, 2) determine the mechanism of allosteric inhibition in caspase-1, and 3) identify natural regulators of caspases acting through the allosteric site. The studies are to include both caspase-1 and caspase-3. Caspases are specific proteases in animals that catalyze the hydrolysis of substrates involved in inflammation and apoptosis. Caspases are implicated in multiple human diseases including arthritis, psoriasis, inflammatory bowl disease, stroke (ischemia), myocardial infarction, sepsis, spinal cord injury, Alzheimer's disease and Parkinson's disease. Previously, only active site inhibitors of caspases have been identified, but show debilitating liabilities as effective therapeutics. An alternative approach is to design inhibitors to an allosteric site that may bypass the problems associated with active site inhibitors. This research will provide further insight into the cellular regulation of caspase activity in vivo and create opportunities to develop a novel class of caspase-targeted therapeutics.